Before I headed out to sea, I did not know a lot about the ocean to begin with. A geologist and geomorphologist by training, I have always looked at the land and had never spent longer in a ship than the 3-hour Wellington to Picton ferry crossing. But it hasn’t taken me long to realise that compared to land, we know so little about our Earth’s oceans.
Aboard the Schmidt Ocean Institute’s vessel, the R/V Falkor, I have joined the science party for two months of voyaging. We are sailing through the Coral and Tasman Seas bathymetric mapping, seabird surveying, studying ocean currents, seafloor magnetic anomalies and sampling for microplastics.
Even though both seas are of incredible importance to New Zealand, Australia, and many neighbouring islands, I have been surprised how little we know about it. The well-studied East Australian Current (made famous by some surfing turtles in Finding Nemo) runs along the coast of Australia but is limited to shallow water depths. In this region where the ocean can be as deep as 4500m, we have no idea how water within these depths moves. On top of that, we are not even entirely sure how the Tasman and Coral seas exist. It is known that they formed from the separation of Gondwana, rifting apart from the Australian continent and stopped opening 52 million years ago (Gaina et al., 1998). But sadly, it is not that simple. Multiple microcontinents and smaller-scale tectonic regimes have started noted, and we do not know how the puzzle fits together yet.
Whilst aboard the R/V Falkor, we have started to fill in some of these gaps. We have mapped over 75,000 km2 in the Tasman and Coral Seas, uncovering seamounts, landslides, fault lines, drowned reefs, canyons, dune fields over 10m tall, mountains taller than Mt Wellington in Hobart or volcanoes taller than Mt Taranaki. We have discovered deep-sea currents deflecting and scouring around this dramatic bathymetry and extensive eddies at the surface and continuing to 700m deep beneath the ocean. We have also found seismic anomalies, evidence that could hold clues on how the Tasman and Coral seas opened. We have counted and sampled over seven thousand seabirds in a remote region of the world where the population had previously just been extrapolated. And we have found microfibres and microplastics at surface waters, but also at depths of 4000m.
The daily excitement of discovery has been incredible, and I have learnt a phenomenal amount whilst becoming immersed in the Taman and Coral Seas. But if we know so little about the oceans on our back doorstep, what do we know about even more remote oceans? It is hard to encapsulate how little we know. Though the ocean covers more than 70% of our Earth’s surface, less than 20% of it has been mapped. Studying our oceans is hard, the logistical issue of penetrating thousands of meters of water still offers extensive challenges to the world’s best engineers and scientists. But just because it is hard does not mean we should shy away. We know about the surface of Mars than we do about our oceans. And based on how much has been found in one small section of the ocean in two months, I think that the most significant challenge and most critical challenge for our cohesion with this planet is not to study other planets but to understand our own.
Alysha Johnson (@AlyshaJohnsonNZ) is a PhD candidate at the University of Wollongong.